Existing infrared imaging devices, such as infrared cameras, are often implemented using a focal plane array (FPA) fabricated on a monolithic silicon substrate. A typical FPA includes an array of bolometers coupled to a read out integrated circuit (ROIC) that translates resistance changes in the bolometers into multiplexed electrical signals representing captured infrared images.
Modern FPAs are becoming more and more complex due to the inclusion of various circuits and components in the ROIC to, for example, compensate for non-uniformities and/or temperature-dependent variations in bolometer outputs. It has also been a modern trend to include various support circuits and components such as, for example, analog-to-digital converters (ADCs) in the ROIC, increasing the complexity of modern FPAs even further.
Such increased complexity has led to many difficulties. For example, as monolithic FPAs become more complex, the yield in fabricating such FPAs may decrease and the cost of designing such FPAs may increase. Moreover, the inclusion of additional circuitry may lead to an increase in die size, which is in conflict with the desire to decrease the size of FPAs for application in small devices. Such problems may be aggravated by the limitations of semiconductor fabrication processes when bolometers and ROIC components are manufactured in monolithic FPAs.